A switch is mounted on a circuit board having a circuit for driving a motor or the like. FIG. 7 shows such a circuit board 2 which is provided on the body 1 of a spindle motor for driving a floppy disk and has a conductor foil pattern constituting a motor drive circuit but not shown in the drawing. A motor drive circuit component 3 is provided on the circuit board 2 correspondingly to the conductor foil pattern. A push switch 4 serving as switch unit is mounted on the circuit board 2 so that the switch is in contact with the lands of the conductor foil pattern. The switch 4 is partly slidably fitted in the board 2 in order to be turned on or off so that the lands electrically connected to external terminals are electrically connected to or disconnected from each other to send out or eliminate an electric signal indicative of the loading of a medium such as a floppy disk. The circuit board 2 includes an iron plate 2a, an electrically insulating layer 2b laminated thereon, and the conductor foil pattern 5 provided on the layer and having a plurality of lines, as shown in FIGS. 8 and 9. The pattern 5 has lands 5a formed at the end portion of conductor foil pattern and opposed to each other at a predetermined distance between the lands 5a. The push switch is disposed at the distance between the lands 5.
The push switch 4 includes a case 41, a pair of fixed contact members 42, and a movable contact member 43. The fixed contact members 42 extend sideward through the wall of the case 41, and are soldered to the lands 5a of the conductor foil pattern 5 so that the fixed contact members 42 are electrically connected to the lands. The movable contact member 43 has a switching rod 43a vertically extending through the top of the case 41 above the circuit board 2, and a coil spring 43b urging the rod upward as shown in FIG. 8 so that the member is normally in pressure touch with the fixed contact members 42 to keep the switch 4 on. When the medium is loaded, the switching rod 43a is pushed in or downward as shown in FIG. 8 against the urging force of the spring 43b so that the movable contact member 43 is put out of touch with the fixed contact members 42 to turn off the switch 4. As a result, the electric signal indicative of the loading of the medium is sent out.
The circuit board 2 is passed through a reflowing furnace with the soldering operation. The push switch 4 is not resistant to heat. Since the switch 4 is manually soldered to the board 2 after the board is subjected to a reflowing process in the furnace, the efficiency of mounting of the switch on the board is low and the soldering is likely to be improperly done to deteriorate the yield of a finished product. If a push switch resistant to heat is used instead of the former, the cost of the product is increased.